This invention relates to electromagnetic circuit breakers of the type disclosed in U.S. Pat. No. 3,290,627, for example.
It is economically desirable to increase the current carrying capacity of circuit breakers by modifying as little as possible, existing circuit breakers. Toward this end, it has been proposed in the past that the amount of current carrying capacity may be approximately doubled by placing two single pole circuit breakers side-by-side (or tripled by using three side-by-side) and connecting the line terminals together and likewise connecting the load terminals together. The resultant "multi-pole" or, preferably, "multi-section" circuit breaker is a single pole circuit breaker in the sense of one current path into and out of the circuit breaker comprised of two or more sections (or "poles").
With such a construction, it is assumed that the current will divide equally through the contacts and through the current sensing devices controlling the tripping of the circuit breaker on overload. It has been found, however, that because the resistance at the contacts varies from section to section of the multi-section circuit breaker, the current will not divide equally among the sections. The result is that nuisance tripping of the circuit breaker has resulted when the unequal division of the current has caused enough current to pass through one of the current sensing devices to cause it to trip its associated mechanism.
It is an object of this invention to combine single pole circuit breakers together to result in multi-section single pole circuit breakers of greatly increased current carrying capacity while also minimizing nuisance tripping.
It is a further object of this invention to provide an economical arrangement for equally dividing the current through the sections of the circuit breaker.